Ethernet Virtual Private Network (E-VPN) is a layer 2 virtual private network (VPN) technology, and is based on Multiprotocol Label Switching (MPLS). In general, an E-VPN network includes customer edge nodes (CEs) such as hosts, routers, and/or switches that form the edge of a customer system connected to an MPLS infrastructure.
Ethernet Ring Protection Switching (ERPS) is an Ethernet ring protection protocol for Ethernet layer network rings or, more generally, for Ethernet Segments (ESs) that are rings. Ethernet rings are often used to provide dual-homed connectivity for an access network to pairs of layer 2 VPN (L2VPN) provider edges. ITU-T G.8032 is an Ethernet ring protection protocol that allows a fail-over to be efficiently provided in the event of a single link, port, or node failure.
Two types of failures may generally occur when an Ethernet Segment is a ring. These two types of failures include provider edge (PE) direct failures and ring partition failures. A PE direct failure includes a PE node failure and failures of a PE attachment circuit. When a PE direct failure occurs, E-VPN Border Gateway Protocol (BGP) prefix-independent convergence (PIC) functionality enables a backup PE node to forward traffic on a ring. A ring partition failure involves failures of elements that are internal to a ring. When a ring partition failure occurs, E-VPN BGP PIC functionality does not enable a backup PE node to forward traffic, as PEs are unable to identify reachable media access control (MAC) addresses behind the PEs. In general E-VPN BGP PIC may effectively prevent a backup node from withdrawing its Ethernet A-D route.
Within a G.8032 protocol, there is no mechanism for differentiating between PE direct failures and ring partitions. Thus, failures are generally not handled in an efficient manner, as proper protection actions for each type of failure are not triggered efficiently.